Automatic flow control devices have been around for hundreds, if not thousands, of years. A large portion of automatic flow control devices are dedicated to maintaining a predetermined fluid level in a reservoir, or tank. Such level maintaining automatic flow control valves have often incorporated elements that float on the surface of the fluid to indicate when the desired fluid level has been obtained. Perhaps the most famous level maintaining automatic flow control valve is that found in the storage tank of a water closet, or toilet. The water closer tank control valve includes a float mounted on a lever that is connected to a shut-off device in the water supply line. When the water in the tank rises to the desired level, the float positions the lever such that it closes the shut-off device, and accordingly the flow of water.
Such float-and-lever control devices appear relatively simple, yet as any homeowner knows, are plagued with problems. Additionally, float-and-lever control devices are not particularly well suited for miniaturization to small-scale application. Further, the level of control offered is relatively crude and not suitable for applications requiring precise level control. Still further, its reliance on an almost constantly submerged lever that must pivot in at least one location is not appropriate for critical applications. Such float-and-lever control devices are found in U.S. Pat. Nos. 3,049,144, 5,655,232, and 5,934,881.
Some automatic flow control devices have recognized the limitations imposed by the lever in the float-and-lever configuration and have incorporated an untethered float configuration. Such untethered configurations are found in U.S. Pat. Nos. 2,169,462; 2,920,644; 2,928,663; and 6,129,836. Still, many such untethered designs suffered from large size requirements and were not suitable for critical applications.
The present invention incorporates two free moving elements that cooperate across a seat connecting two distinct chambers. This configuration supports miniaturization of the automatic flow control device as well as robust operating capabilities, while capable of maintaining the fluid in a reservoir at a predetermined level with great precision.